diff --git a/hgext3rd/age.py b/hgext3rd/age.py
new file mode 100644
--- /dev/null
+++ b/hgext3rd/age.py
@@ -0,0 +1,66 @@
+# age.py
+#
+# Copyright 2017 Facebook, Inc.
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+"""
+a revset predicate for filtering by changeset age.
+
+Adds the `age()` revset predicate.
+
+This revset predicate differs from the built-in `date` by providing a more
+granular way of considering relative time rather than absolute time.
+
+The built-in `date()` predicate does provide full day resolution, so
+`age("<Xd")` is equivalent to `date("-X")`.
+"""
+
+from __future__ import absolute_import
+import time
+import re
+
+from mercurial import (
+    error,
+    registrar,
+    revsetlang,
+)
+
+revsetpredicate = registrar.revsetpredicate()
+
+_rangeparser = re.compile(
+        r'^([<>])(?:(\d+)d)?(?:(\d+)h)?(?:(\d+)m)?(?:(\d+)s?)?$')
+
+@revsetpredicate('age(string)')
+def age(repo, subset, x):
+    """Changesets that are older or newer than a specific age.
+
+    The age range can be specified in days, hours, minutes or seconds:
+
+    - ``<30d``  : Newer than 30 days old
+    - ``>4h30m``: Older than 4 hours 30 minutes old
+    - ``<15s``  : Newer than 15 seconds old
+
+    If no unit is specified, seconds are assumed.
+    """
+    agerange = revsetlang.getstring(x, 'age requires an age range')
+    m = _rangeparser.match(agerange)
+    if not m:
+        raise error.ParseError('invalid age range for age predicate')
+    dirn, days, hours, minutes, seconds = m.groups()
+    cutoff = time.time()
+    cutoff -= int(days or 0) * 60 * 60 * 24
+    cutoff -= int(hours or 0) * 60 * 60
+    cutoff -= int(minutes or 0) * 60
+    cutoff -= int(seconds or 0)
+
+    def newer(x):
+        return repo[x].date()[0] > cutoff
+
+    def older(x):
+        return repo[x].date()[0] < cutoff
+
+    if dirn == '<':
+        return subset.filter(newer, condrepr=('<age %r>', agerange))
+    else:
+        return subset.filter(older, condrepr=('<age %r>', agerange))
diff --git a/tests/test-age.t b/tests/test-age.t
new file mode 100644
--- /dev/null
+++ b/tests/test-age.t
@@ -0,0 +1,87 @@
+
+  $ cat << EOF >> $HGRCPATH
+  > [extensions]
+  > age=$TESTDIR/../hgext3rd/age.py
+  > EOF
+
+Setup repo
+  $ hg init repo
+  $ cd repo
+  $ now=`date +%s`
+  $ touch file1
+  $ hg add file1
+  $ for delta in 31536000 86401 86369 3800 420 5
+  > do
+  >   commit_time=`expr $now - $delta`
+  >   echo "$delta" > file1
+  >   hg commit -d "$commit_time 0" -m "Changeset $delta seconds ago"
+  > done
+
+Check age ranges
+  $ hg log -T '{rev} {desc}\n' -r 'age("<30")'
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age("<7m30s")'
+  4 Changeset 420 seconds ago
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age("<1h4m")'
+  3 Changeset 3800 seconds ago
+  4 Changeset 420 seconds ago
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age("<1d")'
+  2 Changeset 86369 seconds ago
+  3 Changeset 3800 seconds ago
+  4 Changeset 420 seconds ago
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age("<364d23h59m")'
+  1 Changeset 86401 seconds ago
+  2 Changeset 86369 seconds ago
+  3 Changeset 3800 seconds ago
+  4 Changeset 420 seconds ago
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age(">1s")'
+  0 Changeset 31536000 seconds ago
+  1 Changeset 86401 seconds ago
+  2 Changeset 86369 seconds ago
+  3 Changeset 3800 seconds ago
+  4 Changeset 420 seconds ago
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age(">1m")'
+  0 Changeset 31536000 seconds ago
+  1 Changeset 86401 seconds ago
+  2 Changeset 86369 seconds ago
+  3 Changeset 3800 seconds ago
+  4 Changeset 420 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age(">1h")'
+  0 Changeset 31536000 seconds ago
+  1 Changeset 86401 seconds ago
+  2 Changeset 86369 seconds ago
+  3 Changeset 3800 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age(">1d")'
+  0 Changeset 31536000 seconds ago
+  1 Changeset 86401 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age(">365d")'
+  0 Changeset 31536000 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age("<64m")'
+  3 Changeset 3800 seconds ago
+  4 Changeset 420 seconds ago
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age("<60m500s")'
+  3 Changeset 3800 seconds ago
+  4 Changeset 420 seconds ago
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age("<1h500s")'
+  3 Changeset 3800 seconds ago
+  4 Changeset 420 seconds ago
+  5 Changeset 5 seconds ago
+  $ hg log -T '{rev} {desc}\n' -r 'age("invalid")'
+  hg: parse error: invalid age range for age predicate
+  [255]
+  $ hg log -T '{rev} {desc}\n' -r 'age("1h")'
+  hg: parse error: invalid age range for age predicate
+  [255]
+  $ hg log -T '{rev} {desc}\n' -r 'age("<3m2h")'
+  hg: parse error: invalid age range for age predicate
+  [255]
+  $ hg log -T '{rev} {desc}\n' -r 'age(">3h2h")'
+  hg: parse error: invalid age range for age predicate
+  [255]